Comparison of Decay Calculations of ORIGEN-Jül and ORIGEN 2.2

Pohl, Christoph; Nünighoff, Kay

Internal Report

Comparison of Decay Calculations of ORIGEN-Jül and ORIGEN 2.2

Pohl, C.FZJ* ; Nünighoff, K.FZJ*

2010
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag Jülich

Jülich : Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag, Berichte des Forschungszentrums Jülich 4331, 32 p. (2010)

Please use a persistent id in citations: http://hdl.handle.net/2128/3803

Report No.: Juel-4331

Abstract: In this report the depletion codes ORIGEN 2.2 and ORIGEN-Jül were compared with respect to pure decay calculations. For two different isotope compositions (burned low enriched uranium fuel (9.7 wt%), burned plutonium fuel with high fraction of minor actinides) the decay of initial isotope compositions are calculated for certain time periods up to 106 years and the differences of the isotope masses are analysed. It is demonstrated that while the nuclear data used in the codes are slightly different the masse of the isotopes for a given decay time period are in good agreement within the limits of -0.02 % - 0.08 % for burned LEU fuel and -0.3 % – 0.7 % for burned Pu-MA fuel. For safety related assessments, e.g. final radioactivity the occuracy in determination of the isotope mass is dominating. It can be concluded that by calculating nearly equivalent isotope compositions after certain decay time periods both codes therefore will also calculate comparable values of radioactivity and radio toxicity for decay series of individual isotopes. Analysing the relative difference of individual isotope masses significant higher differences could be observed. The largest differences were identified for isotopes with nearly negligible mass fractions. It is shown that these differences are mainly caused by differences of the decay constants and the branching ratios used in ORIGEN 2.2 and ORIGEN-Jül. The influence of additional isotopes considered in the library of ORIGEN 2.2 are negligible. The largest mass fraction in the ORIGEN 2.2 calculation is observed for Pa-234 with 2.1e-16 of the total mass. Nevertheless with respect to precise determination of very small isotope mass fractions an update of the ORIGEN-Jül library to the latest nuclear data (e.g. ENDF/B-VII, JEFF-3.1) should be realised.

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